when very light your AOA is high so is your drag,
NO, AoA is LOW!
in level flight yes, but not in descent. May be I am wrong
You are
Microbusrt
XPMortens wing Cdo (wing only, profile drag only) plot looks fine to me...
It is quite possible ( & common even) for a section to have lower drag at a small +ve Cl than at a lower one, or even zero (take the case of heavy simple camber for instance, that won't like a low alpha!)
I'm just questioning the relevance of laminar flow low drag buckets in this context...